The black WIR SYS 90 ADV SoundPlus Advantage Courtroom System from Williams Sound includes 1 black WIR TX90 infrared transmitter, 5 RX18 receivers, and 1 CHG 518 five bay charger. The TX90 2-channel IR transmitter combines modulator and emitter technology into a single operating unit, which reduces operating costs and eliminates rack space. The TX90 Transmitter produces a wide-angle infrared signal that concentrates the IR energy efficiently in the listening area. Operating on the 2.3 to 3.8 MHz bandwidth, the TX90 is less susceptible to radio and lighting interference. Each TX90 transmitter can cover up to 28,000 sq. ft (2,600 m2) in a single-channel operation. The coverage area can be easily increased by connecting additional TX9 emitters. A wall/ceiling omnidirectional mount is included, and stand kits are available for portable operation.